What Is a Pterosaur?

Part of the Pterosaurs: Flight in the Age of Dinosaurs exhibition.

Dimorphodon 700.309
When the first Dimorphodon was found in 1828 in England, the discovery of a new kind of pterosaur proved that these flying reptiles were varied and had a wide range. 
© AMNH 2014

Neither birds nor bats, pterosaurs were reptiles, close cousins of dinosaurs who evolved on a separate branch of the reptile family tree. They were also the first animals after insects to evolve powered flight—not just leaping or gliding, but flapping their wings to generate lift and travel through the air. They evolved into dozens of species. Some were as large as an F-16 fighter jet, and others as small as a paper airplane.


Pterosaur Evolution

Scientists have long debated where pterosaurs fit on the evolutionary tree. The leading theory today is that pterosaurs, dinosaurs, and crocodiles are closely related and belong to a group known as archosaurs. 

Schleromochlus 700.302
One of the closest early cousins of pterosaurs was probably a small terrestrial reptile known as Scleromochlus taylori, shown here in an artist's rendering.
© AMNH 2014

Pterosaurs were an extremely successful group of reptiles. They flourished all through the age of dinosaurs, a period of more than 150 million years. Over time, the earliest pterosaurs—relatively small flying reptiles with sturdy bodies and long tails—evolved into a broad variety of species. Some had long, slender jaws, elaborate head crests, or specialized teeth, and some were extraordinarily large.

Fragile Fossils

Around 66 million years ago, at the same time that Tyrannosaurus rex and other large dinosaurs became extinct, pterosaurs also died out. Pterosaurs left no descendants—only fossils. But not very many fossils, particularly compared to their dinosaur cousins.

Dawndraco fossil 700.309
This fossil, of the large pterosaur Dawndraco kanzai, was a close relative of Pteranodon longiceps. Parts of the skeleton moved out of place during fossilization. 
© AMNH/C. Chesek

Few pterosaurs lived close to the places where fossils tend to form. Their fragile bones preserved poorly, so pterosaur fossils are frequently incomplete. To form a picture of a particular species, paleontologists must often gather information from several fossils, or draw conclusions from related pterosaurs that are better known.